Technical Abstract:
Snow molds caused by Typhula spp. are the most economically important winter diseases of turfgrass in the northern and alpine regions of the United States and Canada. During winter, the psychrophilic pathogens take advantage of the weakened host plants at low temperatures under persistent snow cover. Snow molds significantly compromise turf quality and delay turf recovery. Given a proper fertility program and cultural practices to promote winter hardness of the plants, the most preferred strategy for managing snow molds is to use resistant cultivars, but there is no known genetics of resistance to snow molds in turfgrass. QTL analysis was used to determine location, number and effect of genomic regions in creeping bentgrass (Agrostis stolonifera) conferring resistance to snow molds in the field. To meet this objective, a full sib mapping population (549 x 372) of creeping bentgrass was planted at two different locations in Michigan and Wisconsin and snow mold severity was evaluated in 2004 and 2005. Snow mold resistance was inherited quantitatively. Fourteen QTLs associated with snow mold resistance were identified on nine out of 14 genetic linkage groups. Effects of some QTLs were dependent on environments, snow mold species or year. We also detected small genomic regions on linkage groups 5.1 and 5.2. associated consistently with snow mold resistance over two locations for two years. These regions had a syntenic relation with previously known QTLs controlling cold tolerance in other Poaceae spp. based on comparative mapping study. Further syntenic relation and genetic basis of the QTLs in creeping bentgrass with C-repeat binding factor (CBF)/dehydration-responsive element-binding protein 1 (DREB1) in perennial ryegrass will be discussed. Markers tightly linked to snow mold resistance QTLs can be very useful for marker-assisted selection in future creeping bentgrass breeding programs.